Deoxyribonucleic acid (DNA) is believed to be the molecular target of a number of clinically useful antitumor agents. The goal of the proposed research is the development of new and more effective DNA reactive drugs for the photodynamic laser-light induced chemotherapy of human cancers or inactivation of viral pathogens or both. Additionally, the study described in this proposal will contribute to existing knowledge of the effects and mechanisms of laser-matter interaction because laser-induced damage to matter especially at cellular and sub-cellular level is poorly understood at this time and is the subject of intense study of many research groups. The aim of the present study is the acquisition and analysis of the absorption spectra, fluorescence spectra and the electrophoretic densitometric traces of DNA and/or some novel mesoionic indole derivatives prior to and subsequent to nanosecond Nd:YAG laser irradiation. Absorption and fluorescence data will be analyzed using Scatchard equation. Photoproducts will be analyzed by HPLC and characterized by CHN elemental analysis and spectroscopically by IR, UV, 'HNMR, 13C NMR and MS.